Heavy Duty Torx Flat Head Tapping Screws

For bulk wholesale from Xiaoguo®, choose our heavy duty Torx flat head tapping screws, a self-drilling fastener requiring no pre-drilling. Featuring a drill-bit tail and a six-lobed countersunk head, it allows you to automatically drill, tap, and lock into metal plates in one simple step using an electric drill, significantly boosting assembly efficiency.

One screw performs three tasks at once: drilling, threading, and tightening. The head is countersunk, and after tightening, it will be flush with the surface of the plate, not protruding, and very smooth. The advantage of the rose-shaped slot is that the drill bit can be firmly inserted, and no matter how hard you tighten it, it will not slip. This Heavy duty Torx flat head tapping screws is particularly suitable for connecting thin iron sheets, aluminum plates, and plastic shells, such as installing color steel tiles on the roof, making ventilation ducts, and fixing the outer shell of the distribution box.

Material Introduction

The material of the Heavy duty Torx flat head tapping screws can be divided into two categories: carbon steel and stainless steel. The choice of material depends on the strength requirements and the installation environment.

Carbon steel

This material is the most commonly used and offers good value for money.

The commonly used grade is 10B21. 10B21 contains boron, which can enhance the hardenability and is suitable for surface hardening.

The strength grades can be either the standard 4.8 grade or the 8.8 grade. Self-drilling screws need to have sufficient hardness to drill through, so they must have a strength of 8.8 grade or above.

For heat treatment, carburizing or carbon-nitrogen co-carburizing must be carried out. The hardness of the drill tail and the threaded surface of the Heavy duty Torx flat head tapping screws is HV 550–700, while the hardness of the core is HV 300–400.

The carbon steel material must undergo surface treatment; otherwise, it will rust during long-term use.

Stainless steel

This material does not require coating and is resistant to corrosion, which is its advantage.

The commonly used grades are A2 (304) and A4 (316).

Because stainless steel cannot significantly increase the surface hardness through carburizing, its drilling performance with drill bits is inferior to that of carbon steel. It can only drill thinner steel plates (thickness ≤ 2 mm) or plastics and woods.

The stainless steel Heavy duty Torx flat head tapping screws have an anti-tensile strength of approximately 700–800 MPa and a hardness of about HV 300–350.

The rust-proofing ability of stainless steel: A2 can withstand general dampness and rain; A4 can resist corrosion from seawater and chloride ions.